how to manage bandwidth on ISA server

i am using ISA server as a proxy server, is there a tool available from which i could specify the bandwidth for each user like if i have 128 KB band width and say i want to give 30 KB to one specific user and 20 kb to another and 1o KB to another specific user

i don't have the links for the websites just yet. but both programs are free from what i can tell. i've installed both and tried them but in terms of features, they only do what they are intended for. and that's limit bandwidth on a per day, week, month or year basis. they don't cap speeds. another program called Bandwidth Controller for Windows caps speeds. but not on a user basic, instead on a network basis. i think it supports subnets, and ips and macs. but not users.
if you ever do find a user based bandwidth capper for isa server let me know. i've been trying to find one. or even a mac based on via manual or automatic registration from a dhcp server. i've been trying to mix the linux NetReg program with isa server stuff but i can't find anything that works.
anyways, hope it helps. but just remember, all three programs are in kinda a beta type form. so it's not 100% sure it will work. and i don't think they cap incoming data, just stuff going out from the internal network. but i might be wrong